Ventilatory care in myasthenia gravis crisis: Assessing the baseline adverse event rate*

Abstract

Myasthenic patients who require mechanical ventilation often develop pneumonia or atelectasis. Although there are differences in the prevalence of these complications among various institutions, there is no evidence that aggressive treatment shortens the course of the myasthenic crisis. We have quantified the severity of lung injury and aggressiveness of respiratory intervention in myasthenic patients admitted to the neuro-critical care unit. We retrospectively identified all mechanically ventilated myasthenic patients admitted in our unit between 1990 and 1998. Neuro-critical care unit of a tertiary care center in an urban area with a large, established, regional neuromuscular disease program. Eighteen myasthenia gravis patients with 24 episodes of respiratory failure requiring mechanical ventilation. A novel respiratory intervention index, comprising the use of suction, intermittent positive-pressure breathing or bronchodilator treatments, sighs, and chest physiotherapy represented the aggressiveness of the respiratory treatment. The respiratory intervention index was correlated with the lung injury score, used as a measure of lung involvement and other respiratory variables. Our patients had less atelectasis and pneumonia than previously published series (46% vs. 91%), leading to shorter mechanical support and neuro-critical care unit stay. The mean respiratory intervention index correlated with lung injury score and inversely with forced vital capacity. This study presents an estimate for both severity of pulmonary complications and intensity of respiratory therapy in the severe myasthenic patient with mechanical ventilatory compromise. Our results suggest that aggressive respiratory treatment should be used in myasthenic patients in crisis to diminish the risk for prolonged respiratory complications. These observations should be validated in a prospective study.